JPWO2013157074A1 - Heat pump device, air conditioner and refrigerator - Google Patents

Abstract

A compressor 1 having a compression mechanism 7 for compressing refrigerant and a motor 8 for driving the compression mechanism 1, an inverter 9 for applying a voltage for driving the motor 8, a converter 10 for applying a voltage to the inverter 9, and an inverter 9 An inverter control unit 12 that generates a drive signal for driving the converter 10 and a converter control unit 17 that generates a drive signal for driving the converter 10, and the inverter control unit 12 includes a heating operation mode in which the compressor 1 is heated. The converter controller 17 has a normal operation mode in which the compressor 1 is normally operated to compress the refrigerant. The voltage is set.

Description

  The present invention relates to a heat pump device, an air conditioner, and a refrigerator.

  As a conventional heat pump device, there is one that supplies a high-frequency low voltage to a compressor during operation stop during heating in order to improve the rising speed at the start of heating of the air conditioner (see, for example, Patent Document 1). . As a similar technique, there is one that supplies a single-phase AC voltage having a higher frequency than that during normal operation to the compressor when the ambient temperature of the air conditioner is detected as being low (see, for example, Patent Document 2).

  In addition, in restraint energization to preheat the compressor to prevent the occurrence of the refrigerant stagnation phenomenon, a stationary output at a predetermined phase angle is performed as a compressor motor drive signal with a PWM output of a two-phase modulation system. Some generate a signal (see, for example, Patent Document 3). Patent Document 4 describes a technique for stepping down an input voltage to an inverter by a converter unit.

Japanese Utility Model Publication No. 60-68341 JP-A-61-91445 JP 2007-166766 A JP 2005-326054 A

  In Patent Documents 1 and 2 described above, a technique is shown in which a high-frequency AC voltage is applied to the compressor in response to a decrease in the outside air temperature to heat or keep the compressor, thereby smoothing the lubricating action inside the compressor. ing.

  However, Patent Document 1 does not have a detailed description of the high-frequency low voltage, and does not consider the output change depending on the stop position of the rotor, so there is a possibility that the desired heating amount of the compressor cannot be obtained. There was a problem.

  On the other hand, Patent Document 2 describes that a voltage is applied by a high-frequency single-phase AC power source of 25 kHz, noise suppression by removing from the audible range, vibration suppression by removing the resonance frequency, and winding. The effects of reducing the input current and reducing the temperature rise due to the inductance of the wire, and suppressing the rotation of the rotating part of the compressor are shown.

  However, since the technique of Patent Document 2 is a high-frequency single-phase AC power supply, as shown in FIG. 3 of Patent Document 2, the entire off section in which all the switching elements are turned off occurs relatively long. . At this time, the high-frequency current is regenerated to the DC power supply without circulating the motor through the freewheeling diode, the current in the off section decays quickly, the high-frequency current does not flow efficiently to the motor, and the heating efficiency of the compressor is poor. There was a problem of becoming. In addition, when a small motor with a small iron loss is used, there is a problem that the amount of heat generated with respect to the applied voltage is small, and the necessary heating amount cannot be obtained with a voltage within the usable range.

  Patent Document 3 discloses a technique for performing preheating so that the rotor does not rotate by performing constrained energization for passing a direct current to the motor windings.

  Further, cited patent document 4 discloses a technique for stepping down an input voltage to an inverter by a converter unit as shown in FIG.

  However, the motor winding resistance tends to become smaller due to the recent high efficiency design of the motor. For this reason, in the preheating method in which a direct current is passed through the motor windings shown in Patent Documents 3 and 4, the amount of heat generated can be obtained by the square of the winding resistance and current, so that the current increases as the winding resistance decreases. It becomes. As a result, heat generation due to increased loss of the inverter becomes a problem, and there are problems such as reduced reliability and increased cost for the heat dissipation structure.

  In recent years, high-efficiency heating is required in order to meet the European EuP Directive (Directive on Eco-Design of Energy-using Products) and Australian MEPS (Minimum Energy Performance Standards), which are strict environmentally conscious design standards.

  The present invention has been made in view of the above, and can efficiently heat a standby refrigerant, and can stably and efficiently realize a necessary heating output, and reduce bearing vibration and noise in the compressor. An object is to obtain a heat pump device, an air conditioner and a refrigerator that can be used.

  In order to solve the above-described problems and achieve the object, the present invention includes a compressor having a compression mechanism that compresses refrigerant and a motor that drives the compression mechanism, and an inverter that applies a voltage that drives the motor. A converter for applying a voltage to the inverter, an inverter control unit for generating a first drive signal for driving the inverter, and a converter control unit for generating a second drive signal for driving the converter, The inverter control unit has a heating operation mode in which the compressor is heated and a normal operation mode in which the compressor is normally operated to compress refrigerant, and the converter control unit is configured to perform the heating of the inverter control unit. In the operation mode, a voltage to be applied to the inverter is set based on a voltage command value for the motor.

  The heat pump device, the air conditioner and the refrigerator according to the present invention can efficiently heat the standby refrigerant, and can stably and efficiently realize the necessary heating output, and reduce the bearing vibration and noise in the compressor. There is an effect that can be done.

FIG. 1 is a diagram illustrating a configuration example of the heat pump device according to the first embodiment. FIG. 2 is a diagram illustrating an example of a detailed configuration of a main part of the heat pump apparatus. FIG. 3 is a flowchart illustrating an example of an execution determination processing procedure in the heating operation mode of the heat pump device. FIG. 4 is a flowchart illustrating an example of an operation procedure in the heating operation mode. FIG. 5 is a diagram illustrating a signal generation method for one phase of the PWM signal generation unit. FIG. 6 is a diagram illustrating eight switching pattern examples according to the first embodiment. FIG. 7 is a diagram illustrating an example of a PWM signal when the high-frequency phase command θk is switched between 0 ° and 180 °. FIG. 8 is an explanatory diagram of changes in the voltage vector shown in FIG. FIG. 9 is a diagram illustrating an example of a phase current, a line voltage, and a PWM signal at a low modulation rate. FIG. 10 is a diagram illustrating the influence of a change in power supply voltage. FIG. 11 is a diagram illustrating the relationship between the breakdown voltage and the on-resistance of the Si device and the SiC device. FIG. 12 is a diagram illustrating a configuration example of the heat pump device according to the third embodiment. FIG. 13 is a Mollier diagram of the refrigerant state of the heat pump apparatus shown in FIG.

  Hereinafter, embodiments of a heat pump device, an air conditioner, and a refrigerator according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a first embodiment of a heat pump device according to the present invention. The heat pump device 100 according to the present embodiment includes a refrigeration cycle in which a compressor 1, a four-way valve 2, a heat exchanger 3, an expansion mechanism 4, and a heat exchanger 5 are sequentially connected via a refrigerant pipe 6. Inside the compressor 1, a compression mechanism 7 that compresses the refrigerant and a motor 8 that drives the compression mechanism 7 are provided. The motor 8 is a three-phase motor having three-phase windings of U phase, V phase, and W phase.

  An inverter 9 that applies a voltage to the motor 8 to drive it is electrically connected to the motor 8. The inverter 9 applies voltages Vu, Vv, and Vw to the U-phase, V-phase, and W-phase windings of the motor 8 using a DC voltage (bus voltage) Vdc as a power source. The inverter 9 is electrically connected to the inverter control unit 12. The inverter control unit 12 includes two operation modes, a normal operation mode and a heating operation mode, and includes a normal operation mode control unit 13 and a heating operation mode control unit 14 that control the respective modes. The inverter control unit 12 includes a drive signal generation unit 16 and a refrigerant stagnation detection unit 25. The drive signal generation unit 16 generates a signal for driving the inverter 9 and outputs the signal to the inverter 9. The refrigerant stagnation detecting unit 25 monitors the stagnation of the refrigerant, and outputs a refrigerant stagnation signal when the refrigerant stagnation is detected.

  In the inverter control unit 12, the normal operation mode control unit 13 is used when the heat pump device 100 performs a normal operation. The normal operation mode control unit 13 controls the drive signal generation unit 16 to output a PWM (Pulse Width Modulation) signal for rotating the motor 8 as an inverter drive signal.

  The heating operation mode control unit 14 is used when the compressor 1 is heated (when a refrigerant stagnation signal is output from the refrigerant stagnation detection unit 25). When the refrigerant stagnation detection unit 25 outputs a refrigerant stagnation signal, the heating operation mode control unit 14 controls the drive signal generation unit 16 to cause the motor 8 to flow by supplying a high-frequency current that the motor 8 cannot follow. A PWM signal for heating the compressor 1 without being driven to rotate is output as an inverter drive signal. At that time, the high-frequency energization unit 15 of the heating operation mode control unit 14 controls the drive signal generation unit 16, and the drive signal generation unit 16 outputs the PWM signal to drive the inverter 9, thereby staying in the compressor 1. The liquid refrigerant thus obtained is warmed and vaporized in a short time and discharged to the outside of the compressor 1.

  The output voltage of the converter 10 is applied to the inverter 9. Converter 10 is driven by converter control unit 17. Converter control unit 17 includes bus voltage command value estimation unit 20, bus voltage control unit 19, and drive signal generation unit 18. Converter control unit 17 generates a drive signal for converter 10 based on the signal from inverter control unit 12 and the signal from bus voltage detection unit 11 (detected value of bus voltage) and outputs the drive signal to converter 10. By controlling the converter 10 in this way, an arbitrary bus voltage is output to the inverter 9.

  FIG. 2 is a diagram illustrating an example of a detailed configuration of a main part of the heat pump apparatus. FIG. 2 shows the configuration of the inverter 9, the converter 10, the inverter control unit 12, and the converter control unit 17. The inverter 9 includes six switching elements (21a, 21d, 21b, 21e, 21c, 21f), and the upper side (the letter representing the upper element is P) and the lower side (the letter representing the lower element is N). ) Of three switching elements connected in parallel. The inverter 9 generates the three-phase voltages Vu, Vv, Vw by driving the switching elements corresponding to the PWM signals UP, UN, VP, VN, WP, WN sent from the inverter control unit 12, respectively. A voltage is applied to each of the eight U-phase, V-phase, and W-phase windings. A bus voltage detection unit 11 for detecting Vdc is provided on the input side of the inverter 9 (supply side of the bus voltage Vdc).

  The heating operation mode control unit 14 of the inverter control unit 12 includes a high-frequency energization unit 15. In FIG. 2, only components that perform characteristic operations in the heat pump apparatus of the present embodiment are described, and the description of the normal operation mode control unit 13 and the like shown in FIG. 1 is omitted. Yes.

  When the heating command unit 24 detects the refrigerant stagnation signal from the refrigerant stagnation detection unit 25, the high frequency energization unit 15 of the heating operation mode control unit 14 generates a high frequency voltage command Vk and a high frequency phase command θk. The voltage command value generation unit 23 of the drive signal generation unit 16 is based on the high-frequency voltage command Vk and the high-frequency phase command θk input from the high-frequency energization unit 15, and the voltages of the three phases (U phase, V phase, W phase). Commands Vu *, Vv *, and Vw * are generated. The PWM signal generator 22 generates a PWM signal (UP, VP, WP, UN, VN, WN) based on the three-phase voltage commands Vu *, Vv *, Vw * and drives the inverter 9 to drive the motor. A voltage is applied to 8. At this time, a high frequency voltage is applied so that the rotor of the motor 8 does not rotate, and the compressor 1 provided with the motor 8 is heated.

  The output voltage of the converter 10 is applied to the inverter 9. The voltage input to the inverter 9 is smoothed by the smoothing capacitor 32 and applied. The converter 10 includes, for example, a reactor 34, a switching element 33 such as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), and a backflow prevention element 35 such as a fast recovery diode. It is a converter. Switching of the switching element 33 is controlled by the converter control unit 17. The output voltage of converter 10, that is, the voltage applied to inverter 9 is detected by bus voltage detector 11.

  Hereinafter, the detailed operation of the heat pump apparatus 100 of the present embodiment will be described using the configuration diagrams of FIGS. 1 and 2 and the flowcharts of FIGS. FIG. 3 is a flowchart illustrating an example of an execution determination process procedure in the heating operation mode of the heat pump apparatus 100.

  The inverter control unit 12 determines whether or not it is in a standby state (compressor 1 is in a stopped state) (step S1). In the standby state (step S1 Yes), the refrigerant stagnation detection unit 25 is placed in the compressor 1. It is determined whether or not the refrigerant has fallen (step S2). When the refrigerant has stagnated in the compressor 1 (Yes in Step S2), the control by the heating operation mode control unit 15 is performed, and the operation is shifted to the heating operation mode to heat the compressor 1 (Step S3). Return to step S1.

  When the refrigerant has not stagnated in the compressor 1 (No in Step S2), the process returns to Step S1 without shifting to the heating operation mode. When it is not in the standby state (step S1 No), the operation of the execution determination process is ended, and the operation process other than the standby state such as the normal operation mode is started.

  FIG. 4 is a flowchart illustrating an example of an operation procedure in the heating operation mode. When shifting to the heating operation mode, the heating command unit 24 of the high-frequency energization unit 15 of the heating operation mode control unit 15 acquires the amplitude of the voltage (output line voltages Vuv, Vvw, Vwu) applied to the motor (step S11). A high-frequency phase command θk is generated and output to the voltage command value generation unit 23 of the drive signal generation unit 16 (step S12). The high-frequency phase command θk is generated, for example, by giving two kinds of angles θ1 and θ2 from the outside by a user operation or the like, and alternately selecting the two at a predetermined cycle. This predetermined cycle may also be given from the outside by a user operation or the like, and the high frequency voltage command Vk may also be given from the outside by a user operation or the like.

  Next, the heating command unit 24 calculates a voltage command V * to be given to the motor 8 based on the necessary heating amount, and outputs it to the voltage command value generation unit 23 (step S13). The necessary amount of heating may be set in advance, for example, or may be set by the designer so as to be changed according to the compressor 1 temperature, the ambient environment temperature, or the like. If the combination of the compressor 1 and the motor 8 is determined, the relationship between the voltage command V * given to the motor 8 and the heat generation amount (that is, the heating amount) is uniquely determined. Therefore, for example, the heating command unit 24 holds the correspondence between the heat generation amount and the voltage command V * in the motor 8 as table data in accordance with the types of the motor 8 and the compressor 1, and the necessary heat generation amount and table data. To obtain the voltage command V *. The amount of heat generated for heating depends on the outside air temperature, the compressor 1 temperature, the bus voltage, and the like. Therefore, instead of holding the correspondence between the required heat generation amount and the voltage command V * as table data, the outside air temperature, the compressor 1 temperature, the bus voltage, etc. and the voltage command V according to the types of the motor 8 and the compressor 1. Is stored as table data, and the voltage command V * is obtained by referring to the table data corresponding to the type of the motor 8 and the compressor 1, the outside air temperature, the compressor 1 temperature, the bus voltage, and the like. Good. Note that the method of calculating the voltage command V * is not limited to the example using the table data. For example, the voltage command V * may be determined according to the amount of heat generated by a predetermined calculation formula.

  Next, the heating operation mode control unit 15 acquires the bus voltage detection value Vdc detected by the bus voltage detection unit 11 (step S14), and a voltage command with a value obtained by multiplying the bus voltage detection value Vdc by 1 / √2. The high frequency voltage command Vk is obtained by dividing V *. Since the calorific value necessary for heating varies depending on the outside air temperature, the compressor 1 temperature, the bus voltage, etc., the high-frequency voltage command Vk is obtained using the bus voltage detection value Vdc in this way, A more appropriate voltage command value can be obtained, and the reliability can be improved.

  The voltage command generator 23 obtains voltage command values Vu *, Vv *, and Vw * for each phase of the motor based on the high frequency voltage command Vk and the high frequency phase command θk, and outputs them to the PWM signal generator 22 (step S15). . The PWM signal generation unit 22 compares the voltage command values Vu *, Vv *, and Vw * of each phase of the motor with the carrier signal having a predetermined frequency and an amplitude of Vdc / 2, and outputs the PWM signals UP, VP, WP, and UN. , VN and WN are generated, the switching elements 21a to 21f of the inverter 9 are driven, and the process is terminated (step S16). Thereby, a voltage is applied to the motor 8 by driving the switching elements 21a to 21f.

  On the other hand, the converter control unit 17 acquires the voltage amplitude applied to the motor 8 from the inverter control unit 12, and the bus voltage control unit 19 has the voltage amplitude smaller than the detected bus voltage Vdc detected by the bus voltage detection unit 11. Whether or not (step S17). When the voltage amplitude is smaller (Yes at Step S17), the bus voltage controller 19 controls the bus voltage command value to be set to 0.5 times the voltage amplitude applied to the motor (Step S18). Specifically, the bus voltage control unit 19 instructs the bus voltage command value estimation unit 20 to set the bus voltage command value to 0.5 times the voltage amplitude applied to the motor, and the bus voltage command value estimation unit 20 The bus voltage command value is determined to be 0.5 times the voltage amplitude applied to the motor. The bus voltage controller 19 calculates the on-duty of the switching element 33 based on the detected bus voltage Vdc and the bus voltage command value determined by the bus voltage command value estimator 20, and calculates the drive signal generator 18. Output to.

  The drive signal generation unit 18 compares the on-duty value with the carrier to generate a drive pulse (drive signal) and outputs it to the converter unit 10 (step S19). Here, the on-duty is a ratio of the on-time of the switching element 33 in the carrier period, and is a value of 0-1. For this reason, the carrier amplitude here may be set to 1. Based on the drive pulse signal thus generated, the switching of the switching element 33 is controlled so that the bus voltage is lowered by the converter operation.

  On the other hand, if the voltage amplitude applied to motor 8 is equal to or greater than the detected bus voltage (No in step S17), converter control unit 17 stops converter 10 (step S20) and does not step down the bus voltage.

  Here, in the above description, the bus voltage command value when the voltage amplitude applied to the motor 8 (voltage applied by the inverter 9 to the motor 8) is smaller than the bus voltage detection value Vdc (voltage applied by the converter 10 to the inverter 9), Although the voltage amplitude is 0.5 times, this magnification is not limited to 0.5 times. Actually, the motor parameters may change depending on the heat generation status of the motor, and the actual heat generation amount of the motor may be different from the desired heat generation amount. In this case, the variation in the amount of heat generation may be considered in advance, and the value may be increased or decreased around a value 0.5 times the amplitude. For example, the voltage amplitude applied to the motor 8 and the bus voltage detection value to be set may be held as a table, and the bus voltage detection value may be set according to the voltage amplitude applied to the motor 8 using the table.

  Next, a method for generating voltage command values Vu *, Vv *, and Vw * in the voltage command generator 23 and a method for generating a PWM signal in the PWM signal generator 22 will be described.

When the motor 8 is a three-phase motor, the UVW phases are generally different from each other by 120 ° (= 2π / 3). Therefore, Vu *, Vv *, and Vw * are defined as cosine waves (sine waves) that are different in phase by 2π / 3 as shown in the following formula (1).
Vu * = Vk × cosθ
Vv * = Vk × cos (θ-2π / 3)
Vw * = Vk × cos (θ + 2π / 3) (1)

  The voltage command generator 23 calculates the voltage command values Vu *, Vv *, and Vw * of each phase based on the high-frequency voltage command Vk and the high-frequency phase command θk, and the calculated voltage command value Vu. *, Vv *, and Vw * are output to the PWM signal generator 22. The PWM signal generation unit 22 compares the voltage command values Vu *, Vv *, and Vw * with a carrier signal (reference signal) having an amplitude Vdc (detected value of bus voltage) / 2 at a predetermined frequency, and the magnitude relationship between them. PWM signals UP, VP, WP, UN, VN, WN are generated based on the above.

  In Equation (1), the voltage commands Vu *, Vv *, and Vw * are obtained by a simple trigonometric function. However, the method for obtaining the voltage commands Vu *, Vv *, and Vw * is not limited to this. There is no problem even if other methods such as phase modulation, third harmonic superposition modulation, and space vector modulation are used.

  Next, a PWM signal generation method in the PWM signal generation unit 22 will be described. FIG. 5 is a diagram illustrating a signal generation method for one phase of the PWM signal generation unit 22. The signal generation method shown in FIG. 5 corresponds to a technique generally called asynchronous PWM. Voltage command signal Vu * is compared with a carrier signal having a predetermined frequency and amplitude Vdc / 2, and PWM signals UP and UN are generated based on the mutual magnitude relationship.

  That is, when the carrier signal is larger than the voltage command value Vu *, UP is turned on and UN is turned off. Otherwise, UP is turned off and UN is turned on. The other phases similarly generate PWM signals.

  FIG. 6 is a diagram showing eight examples of switching patterns in the present embodiment. In FIG. 6, voltage vectors generated in each switching pattern are described as V0 to V7. Further, the voltage direction of each voltage vector is indicated by adding + or − to the name (U, V, W) of each phase, and 0 is indicated when no voltage is generated. Here, + U is a voltage that flows into the motor 8 through the U layer and generates a current in the U layer direction that flows out of the motor 8 through the V phase and the W phase, and −U is V This is a voltage that generates a current in the −U layer direction that flows into the motor 8 through the phase and the W phase and flows out of the motor 8 through the U phase. The same applies to ± V and ± W.

  By combining the switching patterns shown in FIG. 6 and outputting a voltage vector, the inverter 9 can output a desired voltage. When the refrigerant of the compressor 1 is compressed by the motor 8 (normal operation mode), it is generally operated at several tens to several kHz or less. At this time, in the heating mode, by further changing θ at a high speed, a harmonic voltage exceeding several kHz is output, and the compressor 1 can be energized and heated (heating operation mode).

  However, in the case of a general inverter, the upper limit of the carrier frequency that is the frequency of the carrier signal is determined by the switching speed of the switching element of the inverter, so it is difficult to output a high-frequency voltage that is higher than the carrier frequency that is the carrier wave. . In the case of a general IGBT (Insulate Gate Bipolar Transistor), the upper limit of the switching speed is about 20 kHz. Moreover, when the frequency of the high frequency voltage is about 1/10 of the carrier frequency, the waveform output system of the high frequency voltage is deteriorated, and there is a risk of adverse effects such as superimposition of a direct current component. Considering this point, when the carrier frequency is 20 kHz and the frequency of the high frequency voltage is set to 2 kHz, which is 1/10 of the carrier frequency, the frequency of the high frequency voltage becomes an audible frequency region, and there is a concern about noise deterioration. In the present embodiment, the AC voltage synchronized with the carrier frequency can be applied to the winding of the motor 8 by changing the phase θ at high speed, and the AC voltage applied to the motor 8 is outside the audible frequency. Is possible.

  Next, an operation for changing the phase θ at high speed using the high-frequency phase command θk will be described. FIG. 7 is a diagram illustrating an example of a PWM signal when the high-frequency phase command θk output from the heating command unit 24 is switched between 0 ° and 180 °. By switching the high-frequency phase command θk to 0 ° or 180 ° at the timing of the top or bottom of the carrier signal, a PWM signal synchronized with the carrier signal can be output. At this time, the voltage vectors are V0 (UP = VP = WP = 0), V4 (UP = 1, VP = WP = 0), V7 (UP = VP = WP = 1), V3 (UP = 0, VP = WP). = 1), V0 (UP = VP = WP = 0),...

  FIG. 8 is an explanatory diagram of changes in the voltage vector shown in FIG. In FIG. 8, the switching element 21 surrounded by a broken line is on, and the switching element 21 not surrounded by a broken line is off. As shown in FIG. 8, when the V0 vector and the V7 vector are applied, the lines of the motor 8 are short-circuited and no voltage is output. In this case, the energy stored in the inductance of the motor 8 becomes a current and flows in the short circuit. Further, when the V4 vector is applied, it flows into the motor 8 via the U phase, flows into the motor 8 via the V phase and the W phase, flows into the motor 8 via the U phase, the V phase and the W phase. Flows in the U-phase direction (+ Iu current) flowing out from the motor 8 via the V8, flows into the motor 8 via the V-phase and the W-phase, and flows out from the motor 8 via the U-phase when the V3 vector is applied. A current in the −U phase direction (−Iu current) flows through the winding of the motor 8. That is, a current in the reverse direction flows through the winding of the motor 8 when the V4 vector is applied and when the V3 vector is applied. Since the voltage vector changes in the order of V0, V4, V7, V3, V0,..., + Iu current and −Iu current flow alternately in the winding of the motor 8. In particular, as shown in FIG. 8, since the V4 vector and the V3 vector appear during one carrier period (1 / fc), an AC voltage synchronized with the carrier frequency fc can be applied to the winding of the motor 8. It becomes. Further, since the V4 vector (+ Iu current) and the V3 vector (−Iu current) are alternately output, the forward and reverse torques are instantaneously switched. Therefore, it is possible to control the vibration of the rotor to be suppressed by canceling the torque.

Regarding the converter control, when the switching element 33 is turned on, the backflow prevention element 35 is prevented from conducting, and the power supply voltage is applied to the reactor 34. In addition, when the switching element 33 is turned off, the backflow prevention element 35 is turned on, and a voltage is applied to the reactor 34 with the same polarity as when the switching element 33 is turned on due to the energy stored when the switching element 33 is turned on. Be guided. At this time, the relationship between the power supply voltage and the output voltage of the converter is given by Equation (2), and it can be seen that the bus voltage can be adjusted by adjusting the on-duty.
Vdc = D × Vs (2)
Vdc: bus voltage, VS: power supply voltage, D: duty

  Note that a Td interval, which is a non-energized interval, occurs when the bus voltage decreases at the time of a low modulation rate. Unlike the real vector section, the Td section is difficult to control from the PWM signal. FIG. 9 shows an example of a phase current, a line voltage, and a PWM signal at a low modulation rate. When the on-duty is low, a Td interval is generated, and, for example, real vectors V3 and V4 or zero vectors V0 and V7 should be generated, but a transition period from the Td interval to the Td interval and from the Td interval to the zero vector interval Has occurred. Furthermore, as shown in the enlarged view of the phase current and the line voltage shown on the right side of FIG. 9, the dv / dt of the line voltage increases or decreases steeply in the transition period from the Td section to the Td section or from the Td section to the zero vector V7. At high frequencies, a pulse current as indicated by Iw is generated. This is considered to be a short circuit phenomenon due to the capacitance between terminals and the recovery characteristics of the freewheeling diode.

  When such a pulsed current is generated, there is a problem that an increase in loss or malfunction of the apparatus occurs and the stability of the system is impaired. The current on the pulse is several hundred nanoseconds, and it is possible that it may be a source of harmonic noise of megaHz. For this reason, in the present embodiment, the converter control unit 17 performs control so that the modulation rate is set high and the real vector section is set long. Thereby, the energy stored in the L component of the motor in the Td section is reduced, and the pulse current can be suppressed by suppressing dv / dt of the line voltage. Note that generation of a pulsed current can be suppressed by setting the modulation rate to approximately 50% or more.

  FIG. 10 is a diagram illustrating the influence of a change in power supply voltage. When the power supply voltage varies, the area of the line voltage output is constant as shown in FIG. 10, but the di / dt of the output current flowing through the motor winding changes due to the change of the amplitude, and the heating output is changed. The problem of fluctuating occurs. However, since the converter 10 is mounted in the first embodiment and an arbitrary output voltage can be input to the inverter 9 even when the power supply voltage fluctuates, the user can also use the power supply voltage when the power supply voltage varies. Can stably supply the desired heating output.

  Further, in the heating operation mode, by operating at a frequency higher than the operation frequency (up to 1 kHz) at the time of the compression operation and applying a high frequency voltage to the motor 8, no rotational torque or vibration is generated, and the high frequency voltage is applied. By using the iron loss of the motor 8 and the copper loss generated by the current flowing in the winding, the motor 8 can be efficiently heated. The liquid refrigerant staying in the compressor 1 is heated and vaporized by the heating of the motor 8 and leaks to the outside of the compressor 1. The refrigerant stagnation detection unit 25 determines that the refrigerant leakage has been performed for a predetermined amount or for a predetermined time, determines the return from the stagnation state to the normal state, and ends the heating of the motor 8.

  As described above, in the heat pump device 100 according to the present embodiment, when the liquid refrigerant stays in the compressor 1, the phase needs to be changed at high speed, so that the user needs to be highly efficient and desired. The motor 8 can be heated while suppressing noise by flowing a current having a frequency outside the audible frequency (20 to 20 kHz) to the motor 8 by high-frequency energization that satisfies the heating amount. Thereby, the liquid refrigerant staying in the compressor 1 can be efficiently heated, and the staying liquid refrigerant can be leaked outside the compressor 1.

  Further, by setting the ratio of the bus voltage to the amplitude high by the step-down converter (converter 10), it is possible to provide a highly reliable device by keeping the output constant and suppressing the generation of pulsed current. To do.

  Generally, the operating frequency when the compressor is operating is at most about 1 kHz. Therefore, in order to perform heating with high efficiency, a high frequency voltage of 1 kHz or higher may be applied to the motor 8, and when a high frequency voltage of 14 kHz or higher is applied to the motor 8, for example, the vibration sound of the iron core of the motor 8 is almost Since it approaches the audible frequency upper limit, it is also effective in reducing noise. Therefore, for example, the motor 8 may be controlled so as to obtain a high frequency voltage of about 20 kHz outside the audible frequency.

  If the frequency of the high-frequency voltage exceeds the maximum rated frequency of the switching elements 21a to 21f, the element may be destroyed and a load or a power supply may be short-circuited. Therefore, it is desirable that the frequency of the high frequency voltage is not more than the maximum rated frequency for the purpose of ensuring reliability.

  In addition, in the case of a heating device with a frequency exceeding 10 kHz and an output of 50 W, there is a restriction by the Radio Law 100, so that the amplitude of the voltage command is adjusted in advance so that it does not exceed 50 W, and the flowing current is detected to be 50 W or less. By feeding back in this manner, the compressor 1 can be heated in compliance with the Radio Law.

Embodiment 2. FIG.
Next, a heat pump device according to a second embodiment of the present invention will be described. The configuration of the heat pump apparatus 100 of the present embodiment is the same as that of the first embodiment. Hereinafter, a different part from Embodiment 1 is demonstrated.

  In the heat pump apparatus of the present embodiment, the switching elements 21a to 21f shown in FIG. 2 are switching elements of a silicon carbide device (hereinafter, SiC device) that is a wide band gap semiconductor device. FIG. 11 is a diagram illustrating the relationship between the breakdown voltage and the on-resistance of the Si device and the SiC device. At present, the mainstream is generally to use a semiconductor made of silicon (Si). It is known that the SiC device has a larger band gap than the Si device, and as shown in FIG. 11, the trade-off between the breakdown voltage and the on-resistance can be greatly improved. For example, in current induction cookers using Si devices, cooling devices and heat dissipation fans are essential, but by using SiC devices that are wide band gap semiconductor devices, element loss can be greatly reduced, The conventional cooling device and the radiating fin can be downsized or deleted.

  By changing the switching element from the conventional Si device to the SiC device as described above, it is possible to significantly reduce the loss, and it is possible to reduce the size of the cooling device and the heat radiating fins, or to delete the device. Can be made. Further, since switching at a high frequency is possible, it is possible to allow a higher frequency current to flow through the motor 8, reducing the current flowing into the inverter 9 by reducing the winding current by increasing the winding impedance of the motor 8, A more efficient heat pump device can be obtained. By increasing the frequency, it becomes possible to set the drive frequency to a high frequency of 16 kHz or higher, which is the human audible range, and there is an advantage that it is easy to take measures against noise.

  In addition, when SiC is used, an electric current can be made to flow much more with a lower loss than conventional Si, so that an effect such as downsizing of the cooling fin can be obtained. Although the SiC device has been described as an example in the present embodiment, it is obvious to those skilled in the art that a wide band gap semiconductor device such as a gallium nitride-based material or diamond can be used instead of SiC. Only the diode of each switching element provided in the inverter may be a wide band gap semiconductor. A part (at least one) of the plurality of switching elements may be formed of a wide band gap semiconductor. The effects described above can also be obtained when a wide band gap semiconductor is applied to some elements.

  In the first and second embodiments, it is assumed that an IGBT is mainly used as the switching element. However, the switching element is not limited to the IGBT, and a power MOSFET (Metal-Oxide-) having a super junction structure is used. It will be apparent to those skilled in the art that the same applies to semiconductor field-effect transistors), other insulated gate semiconductor devices, and bipolar transistors. The configuration and operation of this embodiment other than those described above are the same as those of the first embodiment.

Embodiment 3 FIG.
FIG. 12 is a diagram showing a configuration example of a third embodiment of the heat pump apparatus according to the present invention. In this embodiment, an example of a configuration and an operation when the heat pump device described in Embodiments 1 and 2 is mounted on an air conditioner, a heat pump water heater, a refrigerator, a refrigerator, or the like will be described.

  FIG. 13 is a Mollier diagram of the refrigerant state of the heat pump apparatus shown in FIG. In FIG. 13, the horizontal axis represents specific enthalpy and the vertical axis represents refrigerant pressure.

  In the heat pump device of the present embodiment, the compressor 51, the heat exchanger 52, the expansion mechanism 53, the receiver 54, the internal heat exchanger 55, the expansion mechanism 56, and the heat exchanger 57 are sequentially connected by piping, and the refrigerant circulates. The main refrigerant circuit 58 is configured. In the main refrigerant circuit 58, a four-way valve 59 is provided on the discharge side of the compressor 51 so that the refrigerant circulation direction can be switched. A fan 60 is provided in the vicinity of the heat exchanger 57. The compressor 51 is the compressor 1 described in the first and second embodiments, and includes the motor 8 driven by the inverter 9 and the compression mechanism 7. Although not shown in FIG. 13, the heat pump device of the present embodiment includes an inverter 9 that drives the motor 8 of the compressor 51, an inverter controller 12, a bus voltage detector 11, a converter 10, and a converter controller 17. Is provided.

  Furthermore, the heat pump apparatus according to the present embodiment includes an injection circuit 62 that connects between the receiver 54 and the internal heat exchanger 55 to the injection pipe of the compressor 51 by piping. An expansion mechanism 61 and an internal heat exchanger 55 are sequentially connected to the injection circuit 62. A water circuit 63 through which water circulates is connected to the heat exchanger 52. In addition, the water circuit 63 is connected to a device that uses water such as a water heater, a radiator, a radiator such as floor heating, and the like.

  The operation of the heat pump device of the present embodiment will be described. First, the operation during heating operation will be described. During the heating operation, the four-way valve 59 is set in the solid line direction. The heating operation includes not only heating used for air conditioning but also hot water supply that heats water to make hot water.

  The gas-phase refrigerant (point A in FIG. 13) that has become high-temperature and high-pressure in the compressor 51 is discharged from the compressor 51, and is heat-exchanged and liquefied in a heat exchanger 52 that is a condenser and a radiator (FIG. 13). Point B). At this time, the water circulating in the water circuit 63 is warmed by the heat radiated from the refrigerant and used for heating and hot water supply.

  The liquid phase refrigerant liquefied by the heat exchanger 52 is depressurized by the expansion mechanism 53 and becomes a gas-liquid two-phase state (point C in FIG. 13). The refrigerant in the gas-liquid two-phase state by the expansion mechanism 53 is heat-exchanged with the refrigerant sucked into the compressor 51 by the receiver 54, and is cooled and liquefied (point D in FIG. 13). The liquid phase refrigerant liquefied by the receiver 54 branches and flows into the main refrigerant circuit 58 and the injection circuit 62.

  The liquid-phase refrigerant that flows through the main refrigerant circuit 58 is heat-exchanged with the refrigerant that flows through the injection circuit 62 (the refrigerant that has been decompressed by the expansion mechanism 61 and is in a gas-liquid two-phase state) by the internal heat exchanger 55, and is further cooled. (Point E in FIG. 13). The liquid-phase refrigerant cooled by the internal heat exchanger 55 is decompressed by the expansion mechanism 56 and becomes a gas-liquid two-phase state (point F in FIG. 13). The refrigerant that has been in the gas-liquid two-phase state by the expansion mechanism 56 is heat-exchanged with the outside air by the heat exchanger 57 serving as an evaporator and heated (point G in FIG. 13). Then, the refrigerant heated by the heat exchanger 57 is further heated by the receiver 54 (point H in FIG. 13) and sucked into the compressor 51.

  On the other hand, as described above, the refrigerant flowing through the injection circuit 62 is decompressed by the expansion mechanism 61 (point I in FIG. 13), and is heat-exchanged by the internal heat exchanger 55 (point J in FIG. 13). The gas-liquid two-phase refrigerant (injection refrigerant) heat-exchanged by the internal heat exchanger 55 flows into the compressor 51 from the injection pipe of the compressor 51 in the gas-liquid two-phase state.

  In the compressor 51, the refrigerant sucked from the main refrigerant circuit 58 (point H in FIG. 13) is compressed and heated to an intermediate pressure (point K in FIG. 13). The refrigerant that has been compressed and heated to the intermediate pressure (point K in FIG. 13) joins the injection refrigerant (point J in FIG. 13), and the temperature drops (point L in FIG. 13). And the refrigerant | coolant (point L of FIG. 13) which temperature fell further is compressed and heated, becomes high temperature high pressure, and is discharged (point A of FIG. 13).

  When the injection operation is not performed, the opening degree of the expansion mechanism 61 is fully closed. That is, when the injection operation is performed, the opening degree of the expansion mechanism 61 is larger than the predetermined opening degree. However, when the injection operation is not performed, the opening degree of the expansion mechanism 61 is more than the predetermined opening degree. Make it smaller. Thereby, the refrigerant does not flow into the injection pipe of the compressor 51. The opening degree of the expansion mechanism 61 is controlled by electronic control using a microcomputer or the like.

  Next, the operation | movement at the time of the cooling operation of the heat pump apparatus 100 is demonstrated. During the cooling operation, the four-way valve 59 is set in a broken line direction. The cooling operation includes not only cooling used in air conditioning but also making cold water by taking heat from water, freezing and the like.

  The gas-phase refrigerant (point A in FIG. 13) that has become high temperature and high pressure in the compressor 51 flows to the heat exchanger 57 side via the four-way valve 59 when discharged from the compressor 51, and is a condenser. The heat is exchanged by the heat exchanger 57 serving as a radiator and liquefies (point B in FIG. 13). The liquid-phase refrigerant liquefied by the heat exchanger 57 is decompressed by the expansion mechanism 56 and becomes a gas-liquid two-phase state (point C in FIG. 13). The refrigerant in the gas-liquid two-phase state by the expansion mechanism 56 undergoes heat exchange with the refrigerant flowing through the injection circuit 62 in the internal heat exchanger 55, and is cooled and liquefied (point D in FIG. 13). In the internal heat exchanger 55, the refrigerant that has become a gas-liquid two-phase state by the expansion mechanism 56 and the liquid-phase refrigerant that has been liquefied by the internal heat exchanger 55 have been decompressed by the expansion mechanism 61, and have become a gas-liquid two-phase state. Heat is exchanged with the refrigerant (point I in FIG. 13). The liquid refrigerant (the point D in FIG. 13) heat-exchanged by the internal heat exchanger 55 branches and flows to the main refrigerant circuit 58 and the injection circuit 62.

  The liquid-phase refrigerant flowing through the main refrigerant circuit 58 is heat-exchanged with the refrigerant sucked into the compressor 51 by the receiver 54 and further cooled (point E in FIG. 13). The liquid-phase refrigerant cooled by the receiver 54 is decompressed by the expansion mechanism 53 and becomes a gas-liquid two-phase state (point F in FIG. 13). The refrigerant in the gas-liquid two-phase state by the expansion mechanism 53 is heat-exchanged and heated by the heat exchanger 52 serving as an evaporator (point G in FIG. 13). At this time, when the refrigerant absorbs heat, the water circulating in the water circuit 63 is cooled and used for cooling and freezing. Then, the refrigerant heated by the heat exchanger 52 flows into the receiver 54 via the four-way valve 59, where it is further heated (point H in FIG. 13) and sucked into the compressor 51.

  On the other hand, as described above, the refrigerant flowing through the injection circuit 62 is depressurized by the expansion mechanism 61 (point I in FIG. 13) and heat exchanged by the internal heat exchanger 55 (point J in FIG. 13). The gas-liquid two-phase refrigerant (injection refrigerant) heat-exchanged by the internal heat exchanger 55 flows into the compressor 51 from the injection pipe of the compressor 51 in the gas-liquid two-phase state. The compression operation in the compressor 51 is the same as that in the heating operation described above.

  When the injection operation is not performed, the opening degree of the expansion mechanism 61 is fully closed so that the refrigerant does not flow into the injection pipe of the compressor 51 as in the heating operation described above.

  In the above description, the heat exchanger 52 has been described as a heat exchanger such as a plate heat exchanger that exchanges heat between the refrigerant and the water circulating in the water circuit 63. However, the heat exchanger 52 is not limited to this, and may exchange heat between the refrigerant and the air. Further, the water circuit 63 may be a circuit in which other fluid circulates instead of a circuit in which water circulates.

  As described above, the heat pump apparatus described in the first, second, and third embodiments can be used for a heat pump apparatus that uses an inverter compressor such as an air conditioner, a heat pump water heater, a refrigerator, or a refrigerator.

  As described above, the heat pump device according to the present invention is useful as a heat pump device capable of efficiently eliminating the refrigerant stagnation phenomenon.

DESCRIPTION OF SYMBOLS 1,51 Compressor 2,59 Four-way valve 3,5,52,57 Heat exchanger 4,53,56,61 Expansion mechanism 6 Refrigerant piping 7 Compression mechanism 8 Motor 9 Inverter 10 Converter 11 Bus voltage detection part 12 Inverter control part DESCRIPTION OF SYMBOLS 13 Normal operation mode control part 14 Heating operation mode control part 15 High frequency electricity supply part 16 Drive signal generation part 17 Converter control part 18 Drive signal generation part 19 Bus voltage control part 20 Bus voltage command value estimation part 21a-21f Switching element 22 PWM signal Generation unit 23 Voltage command value generation unit 24 Heating command unit 25 Refrigerant stagnation detection unit 54 Receiver 55 Internal heat exchanger 58 Main refrigerant circuit 60 Fan 62 Injection circuit 63 Water circuit 100 Heat pump device

In order to solve the above-described problems and achieve the object, the present invention includes a compressor having a compression mechanism that compresses a refrigerant and a motor that drives the compression mechanism, and an inverter that applies a voltage that drives the motor. , comprising a converter for applying a voltage to the inverter, and an inverter control unit for generating a drive motion signal you drive the inverter, a converter control unit for generating a motion signal driving you drive the converter, wherein the inverter The control unit has a heating operation mode in which the compressor is heated by applying a high-frequency AC voltage to the motor, and the converter control unit is connected to the motor in the heating operation mode of the inverter control unit. Then, the voltage applied to the inverter is changed according to the applied voltage .

Claims (10)

A compressor having a refrigerant, a compression mechanism for compressing, and a motor for driving the compression mechanism;
An inverter for applying a voltage for driving the motor;
A converter for applying a voltage to the inverter;
An inverter control unit for generating a drive signal for driving the inverter;
A converter control unit for generating a drive signal for driving the converter;
With
The inverter control unit has a heating operation mode in which the compressor is heated by applying a high-frequency alternating voltage to the motor, and a normal operation mode in which the compressor is normally operated to compress the refrigerant,
The said converter control part sets the voltage applied to the said inverter based on the voltage command value with respect to the said motor in the said heating operation mode of the said inverter control part, The heat pump apparatus characterized by the above-mentioned.   The inverter control unit can set at least one of a frequency, a phase, and an amplitude of a high-frequency AC voltage applied to the motor in the heating operation mode of the inverter control unit by an input from a user. The heat pump device according to claim 1, wherein The converter is a step-down converter that steps down a bus voltage applied to the inverter;
The converter control unit maintains a correspondence between a voltage applied to the motor and a voltage command value for the bus voltage, and sets a voltage command value for the bus voltage according to the voltage applied to the motor based on the correspondence. The heat pump device according to claim 2, wherein   4. The heat pump device according to claim 1, wherein the converter control unit controls the ratio of the voltage applied to the inverter to the voltage applied to the motor by the inverter to be 50% or more. 5. .   The heat pump device according to any one of claims 1 to 4, wherein at least one of the switching elements constituting the inverter is formed of a wide band gap semiconductor.   The heat pump device according to any one of claims 1 to 5, wherein at least one of the diodes of the switching elements constituting the inverter is formed of a wide bandgap semiconductor.   The heat pump apparatus according to claim 5 or 6, wherein the wide band gap semiconductor is silicon carbide, a gallium nitride-based material, or diamond.   The heat pump device according to any one of claims 1 to 7, wherein when the frequency of the high-frequency AC voltage exceeds 10 kHz, the input power of the motor is controlled to 50 W or less.   An air conditioner comprising the heat pump device according to any one of claims 1 to 8.   A refrigerator having the heat pump device according to any one of claims 1 to 8.

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